Heretofore a number of systems have been proposed for reading data, such as digital data information on a data record carrier. Examples of some of the previously proposed systems are disclosed in the following U.S. Patents:
______________________________________ U.S. PAT. NO. PATENTEE ______________________________________ 4,213,040 Gokey et al 4,254,329 Gokey et al 4,353,077 Gokey et al 3,549,897 Blake 3,501,586 Russell 3,624,284 Russell 3,795,902 Russell 3,806,643 Russell 3,885,094 Russell 3,891,794 Russell 4,090,031 Russell 4,163,600 Russell 4,224,481 Russell 3,137,768 Mullin 3,177,476 Robinson 3,387,295 DeMoss 3,564,120 Taylor 3,765,743 Reaves et al 3,898,629 Westerberg 3,919,697 Walker 3,983,317 Glorioso 3,963,863 Malissin et al 4,094,010 Pepperl et al 4,094,013 Hill et al 4,209,804 Dil ______________________________________
The Gokey et al U.S. Pat. No. 4,213,040 and the Gokey et al U.S. Pat. No. 4,254,329 disclose the provision of digital information in rows and columns on a data carrier, in which access and reading is performed with an X-Y transport adapted for skew correction.
The Gokey et al U.S. Pat. No. 4,353,077 discloses an information record which takes the form of a disc in which the rows of information are disposed as straight radial lines, arcuate radial lines or circles with respect to the axis of rotation of the disc.
The Blake U.S. Pat. No. 3,549,897 discloses an absolute electro-optical encoder for indicating the angular position of a shaft. The encoder includes a stationary disc and a rotary disc, the discs having concentric tracks with transmissive and non-transmissive portions which are binarily related. Light passing through the discs is picked up by certain selected combinations of photocells for indicating the position of one disc relative to the other disc.
In the Russell U.S. Pat. Nos. 3,501,586; 3,624,284; 3,795,902; 3,885,094; 3,806,643; 3,891,794; 4,090,031; 4,163,600 and 4,224,481, various "writers" and "readers" are disclosed for "writing" digital data on a spiral track and for "reading" digital data from the spiral track. In the optical encoding and decoding systems described in these patents opaque spots on the track correspond to logic 1 bits of binary data and transparent spots on the track correspond to logic 0 bits of binary data. Also, larger synchronization spots are provided at different places along the track.
The Mullin U.S. Pat. No. 3,137,768 discloses a system for skew correction in a recording and reproduction system. Where skew correction for a film strip having data recorded thereon is achieved by an adjustable deflection arrangement for adjusting the direction of scanning each line in the transverse direction of the film strip.
The Robinson U.S. Pat. No. 3,177,476 discloses an information storage apparatus utilizing a record of internally reflective light conducting material. Here again, data is recorded on spiral record tracks on the recording surface of a disc record.
The DeMoss U.S. Pat. No. 3,387,295 discloses a tape transport system with skew correction. Here a torsionally deformable capstan is controlled by signals representing tape skew of a strip of tape.
The Taylor U.S. Pat. No. 3,564,120 discloses an image construction system with arcuately scanning drop generators. Here an optical scanning system is provided for scanning arcuate lines 21 on a web 82.
The Reaves et al U.S. Pat. No. 3,765,743 discloses an optical energy detection system including an image plane scanning system. Here a scanning wheel is provided for coupling optical energy from a lens to a detector.
An apparatus for scanning a data record medium is disclosed in the Westerberg U.S. Pat. No. 3,898,629 wherein binary digital information is recorded in the form of data along a circular arc and a plurality of such circle arcs of data information are arranged tightly adjacent each other. Here light is directed from a stationary location through a hollow shaft to prisms rotatable on a turntable for directing light down onto a record carrier.
In the Walker U.S. Pat. No. 3,919,697 there is disclosed a data record having track lines which may be separate parallel tracks or may be a single series track of the spiral or raster type.
In the Glorioso U.S. Pat. No. 3,983,317 there is disclosed an astigmatizer for a laser recording and reproducing system. In this system concentric circular tracks are formed in a thermoplastic record or disc by burning selected holes through the disc with a laser. The laser is "on" while the disc is being rotated a short distance to form an elongate data information bit in the track. Then, in reading the data the laser beam or spot is elongated in a direction transverse to the direction of the track with an astigmatizer unit so that a small elongate beam of light with an axis extending transverse to the axis of the track and of the elongate opening therein is used to read the opening.
The Malissin et al U.S. Pat. No. 3,963,863 discloses a device for reading out information recorded upon a substrate. Here a vertically arranged fixed pickup head is positioned about a rotatable carrier with a movable axis of rotation.
In the Pepperl et al U.S. Pat. No. 4,094,010 there is disclosed an optical multi-channel digital disc storage system. Data is stored on a spiral information track and holes corresponding to the information data are burned into the material of the disc by an information radiation beam.
The Hill et al U.S. Pat. No. 4,094,013 discloses an optical storage disc system with disc track guide sectors wherein the data tracks are spiral shaped turns or concentric turns on the disc. The data stored is again in the form of holes burned into the disc.
The Dil U.S. Pat. No. 4,209,804 discloses a record carrier containing information in an optically readable radiation reflecting information structure. With the record carrier of this patent, data is stored in a spiral track on a disc in the form of information areas comprising pits pressed into the record carrier surface or hills projecting from the record carrier surface. According to the teachings of this patent, the depth of the pits or the height of the hills is constant and so is the width of the information areas and intermediate areas at the level of the plane of the lands. Then the information to be conveyed by the record carrier is contained in the variation of the structure of the areas in the tangential direction only. More specifically, the information areas are substantially V-shaped, the phase depth of each information area having one value between 100.degree. and 120.degree. and the angle of inclination between the walls of the information areas and normal to the record carrier are substantially constant and have a value between 65.degree. and 85.degree..
As will be described in greater detail hereinafter the method and apparatus of the present invention differs from the previously proposed methods and appratus by providing steps of or means for sensing a difrerence in an arcuate light beam path and an arcuate row of data on a data record carrier and for correcting the difference which may be a skew correction to place a radius and centerline of the data row into alighment with a radius of the arcuate light beam path on which may be a radius adjustment of the radius of the light beam from its axis of rotation to be substantially the same as the radius of each arcuate data row.
The apparatus also provides electrical-optical transmission means for transmitting optically detected data electrically, optically and then electrically from a turntable to a stationary coupler coupled to a computer. Further the appratus provides a transformer between the turntable and a fixed member for transferring electric power across an air gap to the rotatable turntable.